Paul - sorry to hear that - seems that this can happen with whatever screws you have - I've stripped a couple - luckily they were on a bass so it was one of four on a tuner and I could glue the head back on. DB has done a how to in terms of getting the screws out - may be of some help...
http://www.buildyourownguitar.com.au...ead.php?t=2742